Hidden deep in to the Drainage Design for InfraWorks 360 are some interesting paradigms that Autodesk has taken to reduce some of the mundane tasks of engineering design. For example, when determining the flow to an inlet, one tackles this task in CAD by generating boundaries of the landscaping or green spaces and splits the C value computation into Total Area less pervious area is the impervious area. The overall weighted coefficient is then transferred into the drainage design tool of choice – Excel, Storm Sewers, Storm & Sanitary or your poison of choice, and the analysis repeats for each inlet.
Drainage Design utilizes a rule file called the MaterialMapping2RunoffManningCoeff.clp file to evaluate which engineering property to use. It can be found in the C:\ProgramData\Autodesk\InfraWorks 360\Resources\Standards\Drainage\Common\Rules directory. We don’t have a tool to edit this other than the standard text editors.
Let's examine a couple of the last few lines of this document.
(of RunoffManningCoeff (material "Material/Terrain/Grass") (runoff_coefficient 0.25) (manning_coefficient 0.03) (resolved TRUE))
(of RunoffManningCoeff (material "Material/Terrain/Sand") (runoff_coefficient 0.2) (manning_coefficient 0.03) (resolved TRUE))
(of RunoffManningCoeff (material "Material/Terrain/Stone") (runoff_coefficient 0.45) (manning_coefficient 0.03) (resolved TRUE))
; all user-defined data mapping could be put here...
;(of RunoffManningCoeff (material "Sample Material") (runoff_coefficient 0.0) (manning_coefficient 0.0) (resolved TRUE))
The first three lines above cover three Terrain materials. As you add materials to your library, consider adding these coefficients as well.
Matt Anderson
Product Manager
